To store the encrypted data in a MySQL database, you first have to encode the data so it can safely be written. You can use a blob type for this, but it can make SELECTs really nasty. The easiest way I have found to do this is with base64_encode and base64_decode. The following example using code from a previous example and split into encrypt and decrypt functions.

function EncryptData($source)
{
  $fp=fopen("/etc/httpd/conf/ssl.crt/server.crt","r");
  $pub_key=fread($fp,8192);
  fclose($fp);
  openssl_get_publickey($pub_key);
  /*
   * NOTE:  Here you use the $pub_key value (converted, I guess)
   */
  openssl_public_encrypt($source,$crypttext,$pub_key);
  return(base64_encode($crypttext));
}

function DecryptData($source)
{
  #print("number : $number");
  $fp=fopen("/etc/httpd/conf/ssl.key/server.key","r");
  $priv_key=fread($fp,8192);
  fclose($fp);
  // $passphrase is required if your key is encoded (suggested)
  $res = openssl_get_privatekey($priv_key,$passphrase);
  /*
   * NOTE:  Here you use the returned resource value
   */
  $decoded_source = base64_decode($source);
  openssl_private_decrypt($decoded_source,$newsource,$res);
  return($newsource);
}

Just use the return values to store the encrypted data or display the decrypted data.